WHISTLER WAVE TRAPPING IN A NARROW DENSITY TROUGH

The propagation of linear whistler waves is investigated in a plasma where the field-aligned density trough is produced without electron heating, in the artificial way different from previous experiments. Whistler waves are observed to be trapped in the narrow trough of width 2d≲λ//2d≲λ// (parallel wave length). The phase and amplitude profile of ducted whistlers is measured along and across the trough, controlling the density depth Δne arbitrarily. The transverse amplitude decay outside the trough is found to become maximum at critical frequency. The measured transverse decay-length as well as the wave dispersion is in quantitative agreement with the trapping theory. © 1979, THE PHYSICAL SOCIETY OF JAPAN. All rights reserved.